A pigment appears as a particular color because it selectively reflects and absorbs certain wavelengths of light. When white light, i.e. light having a roughly equal mixture of the entire visible spectrum of wavelengths, encounters a pigment, some wavelengths are absorbed by the chemical bonds and substituence of the pigment and other wavelengths are reflected. The reflected wavelengths determine the color of the pigment. This type of coloring mechanism is based on light absorption and the molecular structure generally reflects a broad range of wavelength with a moderate reflectivity (50-60%). In contrast, nature provides magnificent colors and metal-type reflectors in insects, butterflies, birds and fish. Such colors found in nature are not based on pigments, but on the interference of light reflected from either a nanoscopic multilayer structure of alternative high and low refractive index materials or a regular array of nano-sized particles. These types of nanostructure assemblies can reflect up to 100% of the incident light.
Such types of nanostructure assemblies, for example multilayer structures, have not been exploited for providing narrow reflection bands of electromagnetic radiation. Therefore, there is a need for a multilayer structure that provides a narrow reflection band, and with the reflection band being constant when the multilayer structure is viewed from various viewing angles. As will be explained hereinbelow, the present invention provides for a multilayer structure which may be applied to produce an omnidirectional structural color and/or an omnidirectional narrow band reflector in the visible electromagnetic range. Also explained is a method for making the multilayer structure. These and other advantages of the invention will be apparent from the drawings and discussion presented herein.